Puzzles & Explanations: Create a page to play locally on predefined boards

[kreibaum]

I started this by implementing fen in the backend, adding the move oracle to the websocket and publishing a small group of puzzles under /api/puzzle/.

That should be all the backend I need for this. But turns out I also forgot a lot about how the frontend works :-P

[kreibaum]

So, I'm adding a bit of scope creep to this. What this current concept sets up, is a method to load a game state from FEN and then play on it. This is not getting synchronized over the network so everyone has their own copy.

While this is good for puzzles, I think it also provides a great way to explain the game based on some examples.

In fact, explanations could be an easier first step, because there is no special logic to stop the game if the player doesn't find the right move to capture the king directly.

Ideally, we would then embed this into a long form explanation where new players can learn the rules by directly interacting with the board.